Leaf and neck blast resistance reaction in tropical rice lines under green house condition

Rice blast (Magnaporthe oryzae) is the most destructive and epidemic disease of rice. Use of host resistance is the best alternative for disease management. The leaf and neck blast resistance of 182 rice breeding lines were assessed for leaf and neck blast and classified relative to a susceptible check-Masuli and resistant check-Laxmi, from greenhouse experiment in 2005 and 2006. The test plants were inoculated with 10⁵ conidial suspension/ml of M. oryzae at 21 days old seedlings for the leaf blast, and at neck base for the neck blast. Among them, for leaf blast, 77 rice lines were resistant, 43 were moderately resistant, 39 were moderately susceptible and 23 were susceptible. While among the selected 31 rice lines evaluated for neck blast, 4 lines were resistant, 4 were moderately resistant, 16 were moderately susceptible and 7 were susceptible. Leaf and neck infection was significant and positively correlated (r = 0.30, P = 0.05). The rice lines, Barkhe 1032, Barkhe 1034, Barkhe 1035, Barkhe 1036, Barkhe 2014, Barkhe 2024, Barkhe 3019, Super 3004 were resistant to leaf blast and Barkhe 1006, Barkhe 1032, Barkhe 1035, Barkhe 3004 were resistant to neck blast. The rice lines with identification # 11, 69, 137, 168, 182 from Masuli × MT4 parentage, and Barkhe 3017 were susceptible to both leaf and neck blast. Progenies of Irradiated Pusa Basmati (IPB), Kalinga III/IR64 (KIII/IR64), and Masuli/IR64 were resistant to both leaf and neck blast. However, most progenies from Masuli/MT4 showed susceptible reaction to both leaf and neck blast. Thus, rice lines form the IPB, KIII/IR64 and Masuli/IR64 will be promising resistant sources for rice blast in breeding programme.     

Threonine deaminase: a novel activity stain on polyacrylamide gels

With phenazine methosulfate and nitro blue tetrazolium, an activity stain for threonine deaminase has been developed. Because the deamination reaction does not involve any overall oxidation or reduction, it is proposed that one of the intermediates of the reaction, alpha-aminocrotonate or alpha-iminobutyrate, is the reducing agent. Studies with ferricyanide as the artificial electron acceptor indicate that a decarboxylation of the intermediate occurs during the dye reduction.     

Effect of electrolyte solution on saturated hydraulic conductivity of soils varying in clay type and content,and iron oxides

Changes of hydraulic conductivity (HC) at electrolyte solutions having different combinations of sodium adsorption ratio (SAR)¹ and electrolyte concentration (EC), were monitored in soil columns packed with samples from Rhodustalf, Chromustert, Andic Eutropept and Oxic Rhodustult, four subtropical soils varying in clay type and content, and iron oxides. In general, it was observed that the HC dropped with the decrease of EC and with the increase in SAR of solutions, or, with the increase in exchangeable sodium percentage (ESP) of the soil. In montmorillonitic soils the reduction of HC had been most pronounced, while the kaolinite-rich soils showed only an insignificant drop in HC even at the highest SAR coupled with the lowest EC. The improvement or revival of HC from its final drop was examined upon leaching the soil columns finally with the initial high concentration solution. Montmorillonitic soils showed moderate to high revival of HC, while for montmorillonite-illite-kaolinite mixed clayey soils and kaolinitic soils the improvement of HC was low and practically nil respectively. The percentage revival of HC from its final drop was employed as a criterion to assess the major cause of HC reduction and it was found that irrespective of clay mineralogy “dispersion and subsequent pore plugging” played a major role in reducing the HC of soils, though in montmorillonitic soils swelling had been found to be an almost equivalent additional cause of HC drop. Simple correlations (r) between the saturated HC at varying SAR & EC and different physico-chemical and mineralogical properties have been calculated and its role and implications have been discussed.     

Predicting Metal Uptake and Risk to the Human Food Chain from Leaf Vegetables Grown on Soils Amended by Long-Term Application of Sewage Sludge

The success of risk assessment of metal contaminated soils depends on how precisely one can predict the bio-availability of metals in soil and transfer to the human food chain. In the present investigation, we tested several formulations of the ‘free-ion activity model (FIAM)’ to predict uptake of Cd, Zn and Cu by perpetual spinach (Beta vulgaris, Cicla) grown on a range of soils amended with sewage sludge. The model was parameterised using data measured on samples of pore water extracted by centrifugation and with porous Rhizon samplers installed within the rhizosphere of the growing plants. Free ion activities (M²⁺) were estimated following speciation of solution data using version 6 of the ‘Windermere Humic Aqueous Model (WHAM-VI). For all three metals, the best formulation of the FIAM appeared to require only one hypothetical root sorption site without competition from protons. Values of (M²⁺) could also be predicted satisfactorily from a pH-dependent Freundlich relation. Thus, from a combined FIAM–Freundlich relation and population dietary information, it was possible to estimate risk (hazard quotients) to consumers from very simple soil measurements: extractable metal content (0.05 M EDTA (Zn and Cu) or 1 M CaCl₂ (Cd)), soil humus content and pH. The role of increased soil organic matter content and soil pH, in reducing risk to consumers, is illustrated for Cd in a hypothetical soil at the current UK statutory Cd limit for sludge application to agricultural land.     

Carbon Stock, Afforestation and Acidic Deposition: An Analysis of Inter-Relation with Reference to Arid Areas

Recent advances in desert afforestation underlines its viability and importance in combating global warming and acidification. In this paper, the inter-relation between afforestation, global warming and acid rain has been analyzed. Numerical simulations indicate that afforestation of deserts has distinct advantage as carbon sink and as an important factor for changing microclimate of the region rather than a source of energy. Acidic deposition may well be utilised as fertiliser in nutrient deficit soil of tropical arid areas. However, past trends and projections of acidic deposition in arid areas adjacent to Thar deserts indicate an early efforts are required to cap the opportunity. Delays may contribute towards more incidences of failures.     

Genotype and hormonal effects on callus formation and regeneration in mulberry

Summary Twenty-five mulberry genotypes were studied for callus induction, to evaluate the effectiveness of hormones in promoting callus growth and to identify genotypes capable of regenerating plants. Fifteen genotypes showed callus initiation. Genotypic variation was also noted for longevity and rate of growth of callus cultures. Calli of different genotypes were maintained for more than one year. Frequency of callus initiation was high on Murashige & Skoog's modified medium incorporated with 2.0 mg/l 2,4-D, 100 mg/l casein acid hydrolysate and 150 ml/l coconut water. Regeneration through organogenesis was achieved in six genotypes indicating genotypic specificity.     

Gamma ray-induced genetic manipulations in flower colour and shape in Dendranthema grandiflorum and their management through tissue culture

Rooted cuttings of Dendranthema grandiflorum cv. ‘Puja’ were treated with different doses of gamma rays. Sectorial somatic mutations both in flower colour and shape were detected in all the doses. The original floret colour of ‘Puja’ is red‐purple and florets are flat spoon shaped. One of the mutant floret colour was yellow‐orange with original flat florets and another mutant floret colour was yellow‐orange with tubular florets. Original and mutated ray florets were cultured on agar‐solidified Murashige and Skoog basal medium supplemented with sucrose and different combinations of 1‐naphthaleneacetic acid (NAA) and 6‐benzylaminopurine (BAP). Direct shoot organogenesis was seen within 2 weeks of culture initiation. The best regeneration was obtained on medium supplemented with 1 mg/l BAP + 0.5 mg/l NAA. Shoots regenerated from all explant types were rooted in vitro and transferred to the field. Regenerated plants flowered true‐to‐explant floret colour and shape. The isolated yellow floret colour mutants and yellow floret colour mutants with tubular florets were maintained vegetatively and have proved to be true to type in two successive generations.     

Comparison of Two Adsorbent Based de-Bittering Procedures for Neem (<Emphasis Type="Italic">Azadirachta indica</Emphasis> A. Juss) Tea- Effect on Polyphenols,Anti-Oxidant Capacity,Color and Volatile Profile

Bitterness reduction, especially of foods and beverages containing phytonutrients, is one of the biggest challenges in the food industry because bitterness has a deleterious effect on the taste profile of foods and beverages. Neem (Azadirachta indica A. Juss) is a medicinal tree, indigenous to the Indian-subcontinent, whose medicinal properties have led to it being heralded as the tree which is the “panacea for all diseases”. However, neem leaf is extremely bitter, in large part due to its limonoid content, making it unpalatable. The objective of this study was to apply two adsorbent based strategies, namely solid phase extraction (SPE) and Amberlite XAD-16 (AMB) resin, to achieve de-bittering of neem tea and to determine the effects of the de-bittering on the bio-active, color and volatile properties. The solid SPE treatment completely removed the flavonol, quercetin, from neem tea while in Amberlite XAD-16 treated tea (AMB) it was only insignificantly (p > 0.05) reduced. We also observed decreases in total phenolic content and consequently anti-oxidant activities after de-bittering. A 62% mean reduction of limonoid aglycones indicated diminished levels of bitterness. The loss of phenolics lead to a visually appreciable color changes in the treated teas. The de-bittering also leads to a loss of sesquiterpenes, ketones and acids from neem tea. In conclusion, we found that while SPE cartridges were more efficient in removing bitterness, they caused a greater reduction in bio-active compounds than AMB XAD-16 resins, which may ultimately affect the health properties of neem tea.